1. Field of the Invention
This invention relates to the manufacture of forks, for use in fork lift trucks, and of like members from rolled steel sections.
2. Description of the Prior Art
Forks for fork lift trucks comprise two arms disposed substantially at right angles to one another, one arm having a tapered end portion for engagement under loads to be lifted and the other arm having a hook for engagement over a support member on the fork carriage riding on the mast of a fork lift truck.
Such forks have hitherto been made from rolled steel solid sections or strip. The taper is formed on one end portion of the section or strip as by forging and then the section or strip is bent about its mid portion by conventional bending methods. This bending is normally effected by drop forging and then the forks thus formed are subjected to heat treatment for example in a rotary furnace to provide the forks, especially at the angle, to the degree of hardness desired. Such methods have the disadvantage that they take a long time and require the expertise of forge-masters which results in a high cost of production. Also the crystalline structure of the section or strip tends to change during the bending and thus does not have the optimum crystalline condition.
It has been proposed to bull weld two arm sections together at right angles but this necessitates disposing the arm ends at right angles with one shaped arm end almost abutting the side of the second arm with a small gap e.g. 2 mm between them. The shaped end of the first arm has cutaway portions and these cutaway portions form, with the second arm, cavities into which weld metal is welded. This method is slow and the free end of the second arm adjacent the weld has to be ground or otherwise mechanically shaped to form a satisfactory smooth surface at the outside angle of the bend formed at the welded joint while the inside angle must be rounded with weld metal. This has proved to be expensive and time consuming and the necessary crystalline condition of the metal at the bend may have to be provided by heat treatment.
The main object of the present invention is to provide an improved process for the production of such forks in which the aforesaid disadvantages are reduced to an acceptable minimum.